1. How solar power gets into your car
Your panels turn sunlight into direct current (DC) electricity. An inverter, either one box on the wall or small microinverters under each panel, turns it into the alternating current (AC) your home uses. Your Level 2 charger passes that AC to the car, and the car's onboard charger turns it back into DC to fill the battery.
Every step loses a little energy. That's already counted in two places: our calculator allows 18% for losses between sunlight and your outlet, and the EPA's kWh-per-100-miles rating for each car is measured at the wall, so it already includes the energy lost while charging. You don't need to add a third allowance on top.
2. How many panels a typical commute needs
A Tesla Model Y Long Range uses about 29 kWh per 100 miles (EPA). Driving 35 miles a day takes about 10.1 kWh. With the US average of about 4.98 peak sun hours a day and 18% losses, each 1 kW of panels makes about 4.1 kWh a day, so the car needs about 2.5 kW of panels: 7 panels of 400 W.
Sunshine changes the answer. In Arizona (about 6.5 peak sun hours) the same car needs 5 panels; in Washington state (about 4 hours) it needs 8. Our 50-state study lists every state, and the calculator works it out for your car and mileage.
3. Three ways to use your solar for charging
Making enough solar over a year is only half the story. The other half is timing: panels make power at midday, but many people charge at night. There are three ways to bridge that gap.
| Setup | How it works | Extra cost | Best for |
|---|---|---|---|
| Charge while the sun shines | The car charges straight from your panels during the day | None (a solar-aware charger helps) | People who work from home, retirees, weekend charging |
| 1:1 net metering | Daytime solar goes to the grid for full credit; the credit pays for night charging | None | Homes in states that still offer full retail credit |
| Home battery | A battery stores midday solar and charges the car in the evening | About $13,500 for a Tesla Powerwall 3, installed | Net billing areas like California, or homes that want outage backup |
What the table means
If your car is home during the day, direct charging is the simplest and cheapest option: the power goes straight from the roof to the car with no extra equipment.
If you charge at night, your utility's rules decide what your solar is worth. With 1:1 net metering, the grid works like a free battery. Under net billing, such as California's NEM 3.0, exported solar earns only a few cents, so cheap off-peak charging, daytime charging or a battery become important. A battery also loses some energy each time it stores and releases power, typically around 10%.
4. Matching your charger to your panels
A basic Level 2 charger pulls full power the moment you plug in. A 48-amp charger draws about 11.5 kW. If your panels are making 5 kW and your house is using 1 kW, only 4 kW of the charging comes from the roof; the other 7.5 kW comes from the grid.
A solar-aware charger fixes that by speeding up and slowing down to match your spare solar. Chargers such as the Emporia Pro, Enphase IQ EV Charger 2 and Wallbox Pulsar Plus (with its power meter) can do this for almost any EV. Tesla owners can use Charge on Solar in the Tesla app, but it needs a Tesla Powerwall at home; a Wall Connector on its own can't do it.
5. What it costs
The 30% federal tax credit for home solar ended for systems installed after December 31, 2025, so our calculator uses the full installed price of about $3.00 per watt. Seven panels (2.8 kW) cost about $8,400.
Spread over 25 years of output, that works out to roughly 7 to 10 cents per kWh depending on your state's sunshine, compared with the US average grid price of about 18 cents (EIA, July 2026). For a Model Y, that's about 2 to 3 cents a mile, against about 15 cents a mile for a 28 MPG gas car at October 2026 gas prices.